San Francisco authorities plan to issue fines ranging from $45 to $300 once they've warned people about tossing food to pigeons. The move is needed to clean up some areas of the city, officials say.

SAN FRANCISCO — Despite two warnings by police in the last month, David Carpenter says he can't bring himself to stop feeding the pigeons.

He's read the city's flier explaining why feeding the birds causes a population explosion, yet he still tossed remnants of his sandwich on the street last week.

Several weeks ago, city officials began cracking down on people who feed pigeons in the Tenderloin area and, in the next month, plan to extend the enforcement effort to Fisherman's Wharf, Chinatown and Hallidie Plaza, the cable car turnaround in downtown.

"I think it's ridiculous," Carpenter said. "I'm just an animal guy."

But the 42-year-old Tenderloin resident says that he has gotten the message and that he no longer buys a loaf of bread every week to feed the birds.

City officials say they will issue fines ranging from $45 to $300 once they have warned people about feeding the birds. First, though, the city is trying to get the word out about the ban. They are posting fliers in store windows and will begin placing notices in bus shelters this month.

"We have a whole education campaign letting people know it's against the law," said Christine Falvey, spokeswoman for the Public Works Department. "It damages property, and it's not good for the bird population."

And, she said, what the birds don't eat attracts rats.

City officials began targeting people who feed the birds after a recent effort to spruce up the Tenderloin neighborhood. Workers filled potholes, cleaned sidewalks and streets, painted over graffiti and set up a complaint hotline.

After they were inundated with calls about the mess caused by pigeons, officials began working on the problem, Falvey said.

In addition to tourists and office workers who toss lunchtime crumbs to the birds, officials say they have been plagued by more committed feeders who dump huge bags of seeds in empty lots or on sidewalks and then leave. One of those feeding spots was outside Boeddeker Park in the Tenderloin.

"We have sent warnings to about three individuals who are constantly feeding these birds," said Mohammed Nuru, operations director for the Public Works Department. "One man downtown, known as 'Pigeon Man,' walks with a bag around his back and throws out seeds. He has all these pigeons following him."

Another woman shows up at Justin Herman Plaza with a big black bag full of doughnuts and bagels for the pigeons, he added.

But those who don't cooperate could face stiff penalties. A ticket from the Police Department carries a $45 penalty; the Public Works Department can enforce an anti-littering law with penalties ranging from $150 for the first offense to $300 for a third.

Nuru says cleaning up after pigeons takes a lot of time and effort. To flush droppings off the streets of the Tenderloin, his workers use power washers.

Property owners face the expense of removing droppings from building overhangs and ledges, where pigeons build nests, Nuru says.

"You can always tell if you have a feeder if you look up and see the birds roosting and nesting," said Carl Friedman, director of San Francisco Animal Care and Control.

Sometimes gentle persuasion doesn't work.

Friedman said one persistent feeder, a Russian immigrant, wouldn't stop leaving treats for pigeons in the Sunset district when asked to do so by the city. Finally, officials contacted the man's family, and impressed upon them that he could be arrested. That worked.

Sausalito, just across the Golden Gate Bridge, couldn't stop one person until it passed a ban in January on giving treats to pigeons, said Police Chief-Assistant City Manager Joseph Kreins.

"He wouldn't stop until the ordinance went into effect," Kreins said. "Once it went into effect, he said he would stop, and he did."

The chief said the ordinance, which imposes a $50 fine for feeding, appears to be working. No one has been cited and business owners tell him there are fewer pigeons.

Last year, Sausalito restaurateurs, hotel operators and other merchants complained about flocks of pigeons damaging their businesses. The owner of one hotel on the bay even resorted to spending $35,000 on twirling metal roof devices to keep the birds from perching.

In other areas, Friedman said, the city wants people to let the birds scavenge for seeds, grain, fruit and insects.

But Richard Higginbotham, a 50-year-old computer operator who tossed tortilla chips to a flock of pigeons on the landing of a downtown subway station recently, wondered where in this urban environment, with little greenery, the pigeons could find such food.

"They look like city birds," he said. "Their feathers are all disheveled. They are rough and hardened. It looks like they need to be fed."